Nonabsorbent roller applicator

ABSTRACT

A roller applicator for treating plants with herbicides and other fluids comprises a nonabsorbent textured roller, a low-pressure fluid delivery system, and means for collecting and recirculating the fluid. The components of the apparatus act in cooperation with one another so as to minimize loss of material by drippage, spray drift, and holdup in the components of the device. The applicator can be used with solutions as well as wettable powders, emulsifiable concentrates, and other multiphase formulations without separation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

In recent years considerable attention has been given to the rollerapplicator for applying solutions of herbicides for the control of weedsgrowing amongst field crops. It is particularly useful late in theseason for eradicating weeds and other volunteer plants protruding abovethe crop canopy and posing a problem during harvest. The rollerapplicator is designed to selectively dispense herbicide solution to thetarget plants by direct contact with an absorbent roller. The mostcommon type utilizes carpet as the absorbent covering and is thuscommonly referred to as a "carpet roller." A major problem with carpetrollers has been maintenance of the proper level of surface moisture forweed control. Drippage of the saturated carpet is minimized bycontinuous turning of the roller. When the roller is stopped, excessivedrippage onto crops occurs due to the extensive fluid retained in thecarpet material. This results in both crop damage and waste ofherbicide. Emulsions and suspensions of wettable powders are notpractical to use with carpet rollers because of phase separation inducedby the filtering effect of the fiber pile. Likewise, the fibers caninduce a salting-out of some formulations. Both types of separationresult in a reduction in the effectiveness of the herbicide and abuildup of residue in the carpet, thereby limiting carpet rollers foruse with only soluble materials. The present invention relates to aroller applicator which resolves these difficulties.

2. Description of the Prior Art

The problem of moisture control on carpet rollers has been addressed byBertness (U.S. Pat. No. 4,253,272), Burnside (U.S. Pat. No. 4,223,479),and Schepers et al. (U.S. Pat. No. 4,265,048). In each of these patents,the moisture content of the roller is monitored as a function of anelectrical value, and a system responsive to that value controlssubsequent wetting of the carpet. Despite limited effectiveness of suchsystems, carpet rollers nonetheless remain susceptible to theaforementioned separation and cleaning problems. Keeton (U.S. Pat. Nos.4,346,531 and 4,347,684) discloses an applicator in which the rollercomprises a bare, hard plastic tube. A similar arrangement is taught byLohoar in U.K. Pat. No. 2,083,732. However, in each case, absorbentmaterials are used to transfer liquid from the storage reservoir to theroller, thereby preempting any advantage relating to cleaning andavoidance of phase separation.

SUMMARY OF THE INVENTION

I have now devised a roller applicator which is universally applicableto all types of agronomic liquids and which avoids virtually all loss ofmaterial to nontarget areas. The applicator is designed to minimize theamount of nonrecoverable liquid as holdup, thereby facilitating cleaningand changing from one material to another.

The essential features of the invention include a nonabsorbent texturedroller, a means for delivering liquid to the roller under low pressure,and a wiper system for spreading the liquid into a thin film on theroller surface and for channeling the excess into collectors forsubsequent recirculation. The agitation imparted by the wiping andrecirculating mechanisms is sufficient to maintain the integrity ofmultiphase formulations including emulsions, dispersions, andsuspensions. Drippage is controlled under all conditions of use byvirtue of surface tension between the thin liquid film and the texturedroller surface.

In brief, it is an object of the invention to design an economical fluidapplicator for plants with low capital cost and minimal use of fluidrequired for effective treatment.

It is also an object of the invention to design a roller applicatorwhich is functional with virtually all types of liquid-basedagricultural chemicals, especially herbicides.

Another object of the invention is to provide a roller applicator whichis easy to drain and clean and which does not present a pollution hazardin the cleaning vicinity.

A further object of the invention is to provide a roller applicatorwhich can be used on sloping terrain without drippage or spillage andwhich does not produce spray drift under windy conditions.

Other objects and advantages of the invention will become apparent fromthe ensuing description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the nonabsorbent roller applicator ofthe invention.

FIG. 2 is a front elevation view of the applicator shown in FIG. 1.

FIG. 3 is an enlarged sectional view taken along line 3--3 in FIG. 2.

FIG. 4 is a detail view of the roller surface illustrating oneembodiment of the texture.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the roller applicator of the invention generallydesignated by the numeral 10 is most advantageously mounted by anysuitable means on the front of a tractor 1 so as to be adjustable in thevertical direction. For example, it can be secured to the tool bar orattached to the cylinder arms of a front loader. Front mounting avoidsdislocating target plants away from the roller by the passing vehicle.It also facilitates the visual facets of operation such as accommodatingthe height of the device to changing conditions. A reservoir 5 forstoring the chemical is also mounted on the tractor or optionally can besecured directly to the framework of the applicator itself.

The applicator comprises as its principal component a roller 11 having anonabsorbent, textured surface 12. The roller is preferably constructedfrom a noncorrosive material such as rigid polyvinyl chloride (PVC)tubing. Of course other materials as known in the art would beequivalent to PVC for this purpose provided that they are impermeable toliquids. The texture should be sufficiently pronounced so that thesurface tension between the liquid and the roller surface willcounteract the cohesive forces of the liquid and inhibit its tendency to"bead" on the roller surface. When the liquid is properly spread ontothe roller, it will thereby form a thin, uniform film which will beeffectively transferred to target plants. The term "uniform" is usedherein to denote uniformity of the average film thickness across thelength of the roller with the understanding that there may be somevariation in actual thickness across the relief of the texture. Thetexture can be formed by any conventional technique such as molding,etching, machining, or covering with a nonabsorbent fabric. For example,FIG. 4 illustrates the effect of covering the tubing with fiberglassinsect screen and sealing the screen with epoxy resin. The result is apattern of alternating ridges 13 and depressions 14 which are 1-2 mm.deep and 2-3 mm. in diameter.

Referring to both FIGS. 2 and 3, the roller 11 is mounted to berotatably driven by motor 16 through a reduction gear 17 and chain drive18. It is essential that the roller be rotated so that the leading(forward) edge of its surface moves in an upward direction. Thus, as theapplicator advances through the field, the effect of frictional contactbetween the roller and the plant tends to support the plant in anupright position while the fluid is wiped on the stem and underside ofthe leaves. For reasons which will become apparent from the ensuingdescription, direction of rotation is also important to loading of fluidon the roller surface 12. The rotational speed is not necessarilycritical but will typically be set within the range of 20-60 r.p.m. Byuse of a variable speed motor, the rate of rotation can be adjusted toinstantaneous demand.

The herbicide or other fluid held in reservoir 5 is delivered by gravityor low pressure pump (not shown) to manifold 20 through supply line 21optionally fitted with shutoff valve 22. The manifold distributes thefluid to a plurality of nozzles 23 mounted on shield 24. Sealinglyattached to the lower end of shield 24 is a flexible wiper blade 25preferably constructed of rubber or other pliable material and biasedagainst roller surface 12. The fluid emitted from nozzles 23 flows intothe space 31 defined by the roller on the one side and the shield 24 andwiper blade 25 on the other. Due to the low pressure of nozzles 23 andthe protection provided by the roller and shield, loss of liquid bybacksplatter and spray drift is virtually nil. The wiper blade 25functions as a weir causing the fluid to spread out along the fulllength of the roller. Holes 27, one on either end of the blade, permitexcess fluid to drain into trough 30, thereby preventing spillage fromthe ends of the device. On the forward edge of trough 30 is mounted asecond wiper blade 32 which is also preferably constructed from apliable material such as rubber. Blade 32 is biased against the rollersurface as shown so as to squeegee the fluid into a thin film with thesurplus flowing down into trough 30. Wipers 25 and 32 also conjointlyserve to prevent spillage from the trough and to protect it from entryof plant debris and dirt.

Fluid collected in the trough is recirculated either to manifold 20 orreservoir 5 by means of low-pressure pumps 32A and 32B positioned oneither end. While any conventional pump arrangement would be operable,continuously run electric pumps powered by the electric system of thetractor are preferred for the sake of simplicity and reliability.Screens (not shown) positioned at the intake of each pump will collectany debris which happens to enter the system. When recirculating thefluid to the manifold, it is advantageous for line 33A from the rightpump 32A to be connected to the manifold near its leftmost end, and forthe line 33B from the left pump 32B to be connected to the manifold nearits rightmost end. In this manner, when the apparatus is on an incline,there will be at least partial compensation for the gravitational effecton the nozzle output along the length of the manifold. By inserting aT-valve 34 in each of the lines 33A and 33B, virtually all unused fluidat the completion of a field treatment can be pumped back to reservoir5.

As previously mentioned, the present invention can be used to treatplants with a variety of chemical formulations inclusive of solutions,suspensions of wettable powders, emulsifiable concentrates, and thelike. Due to the nonabsorbency of the component parts, the liquid holdupin the system at any given time is minimal. Consequently, the apparatusis especially suited for use with low volumes of highly concentratedformulations. In agriculture, the principal application is for use withherbicides in rescue weed control prior to harvest. Along roadways andother public right-of-ways, the instant device offers potential as anenvironmentally safe alternative to broadcase spraying. In general, itwill have utility wherever rope wick applicators and carpet rollers havebeen used.

It is understood that the foregoing detailed description is given merelyby way of illustration and that modification and variations may be madetherein without departing from the spirit and scope of the invention.

What is claimed is:
 1. A contact roller-type apparatus for applying afluid to plants and adapted for mounting on a vehicle, said apparatuscomprising:a. a reservoir for storing said fluid; b. a roller adaptedfor rotation about a generally horizontal axis and having a nonabsorbenttextured surface for applying the fluid to the plants as the leadingedge of the roller surface contacts the plant when the vehicle is movedin a forward direction, wherein the surface texture is sufficientlypronounced to inhibit the tendency of the liquid to bead on the rollersurface; c. means for rotating said roller such that the leading edge ofthe surface moves in an upward direction; d. delivery means comprising aplurality of low-pressure nozzles spaced along a line parallel to thetrailing edge of the roller and communicating with the reservoir bymeans of a manifold, wherein the nozzles are adapted to deliver thefluid directly to the roller surface; e. wiper means for spreading saidfluid delivered to the roller surface into a substantially uniform filmacross the length of the roller and for removing excess fluid from thesurface, said wiper means comprising first and second wiper bladesparallel to the axis of said roller and biased against the rollersurface along virtually the entire length of the roller and adapted tochannel the excess fluid into a collecting means wherein said secondwiper blade is positioned near the forward edge of said collectingmeans; and f. means for collecting the excess fluid and recycling it tothe reservoir or the delivery means, wherein said collecting meanscomprises a trough generally positioned below the roller, extending atleast the length of the roller parallel to its axis, and spaced apartfrom the roller surface.
 2. An apparatus as described in claim 1 furtheradapted for mounting on the front of said vehicle.